1. Department of Applied Science, R.O.C. Naval Academy, No. 669 Junxiao Road, Kaohsiung 81345, Taiwan
2. Center for Nanoscience and Nanotechnology, National Sun Yat-sen University, No. 70 Lien-hai Road, Kaohsiung 80424, Taiwan
3. Department of Physics, National Sun Yat-sen University, No. 70 Lien-hai Road, Kaohsiung 80424, Taiwan
4. The Center of Crystal Research, National Sun Yat-sen University, No. 70 Lien-hai Road, Kaohsiung 80424, Taiwan
5. Electrical Engineering and Computer Science, University of Michigan, No. 1301 Beal Avenue, Ann Arbor, Michigan 48109-2122, United States
6. Department of Materials and Optoelectronic Science, National Sun Yat-sen University, No. 70 Lien-hai Road, Kaohsiung 80424, Taiwan
7. Department of Electronics Engineering and Institute of Electronics, National Chiao Tung University, No. 1001 University Road, Hsinchu 30010, Taiwan